1796 Light Cavalry Sabre B Markings

[Pat]

Hi everyone,

I recently received a 1796 light cavalry sabre, and I'm not sure what to make of two B's that are stamped into the spine of the blade. The seller stated that they indicate the blade was made in Birmingham, which seemed plausible considering the scabbard reads Woolley, Deakin and Dutton. However, after some googling, another seller says they are bench test marks. I don't know what to believe now, so do any of you have more information on these markings? One is located at the point of balance 18.2 cm / 7.16" from the guard, and the other one about 12 cm / 4.7"further down the blade towards the point.

Thanks